1. Description of the Invention
The present invention relates to the brewing of coffee and more particularly pertains to new and improved coffee brewing methods and apparatuses which permit the rapid brewing of ground coffee, one cup at a time, without the necessity of utilizing expensive and cumbersome coffee percolators and the like.
2. Description of the Prior Art
At the outset, it is to be understood that the terminology "ground coffee" and variations thereof, e.g., "coffee grounds," is illustrative in scope and includes all forms of coffee utilizable in an extraction brewing process, as opposed to completely soluble forms of coffee such as commercially available and commonly labeled "instant coffee." Accordingly, the terminology "ground coffee" may include pulverized coffee, chopped coffee, insoluble dried PG,4 coffee, etc., and may in some cases, even include whole coffee beans.
As can be appreciated, coffee is one of the more popular beverages consumed in the United States, as well as in many other countries around the world. As is well known in the art, coffee is normally brewed from ground coffee beans and the quality of the brewed coffee is dependent upon several factors. In this respect, the most desirable quality is obtained when the coffee is brewed directly from roasted ground coffee beans. Inasmuch as freshly-ground coffee will become substantially stale in approximately seven days, manufacturers have resorted to packaging the freshly-roasted ground coffee in vacuum-sealed containers and in this manner, the ground coffee will remain reasonably fresh for a peiod of about five to six months. However, once the vacuum seal of a particular container has been broken, the quality of the coffee will begin to deteriorate whereby staleness will be evident in about seven or less days.
While ground coffee is the most desirable form of coffee to brew, inasmuch as it has the most distinct aroma and flavor characteristics, considerable difficulty is normally experienced in effecting such brewing. For example, virtually all currently-known methods of brewing ground coffee involve the use of cumbersome and expensive equipment which is slow in operation, which normally requires the brewing of substantially more coffee than is needed, and which is then difficult to clean and store. Further, it should be noted that coffee beans are composed of about 300 different chemicals, many of which enter into solution in a brewed coffee mixture. More particularly, soluble coffee solids consisting of different chemical compositions are extracted from roasted ground coffee at variable rates, with each of these compositions contributing to the production of taste and aroma normally associated with freshly-brewed coffee. Even a slight variation in the amounts of these various chemical compositions can result in a substantial and dramatic difference in both taste and aroma. As such, freshly-brewed coffee is usually at its peak of aroma and flavor immediately after brewing, and it begins to deteriorate in quality immediately thereafter. Typically, in about 20 minutes after brewing, the flavor and aroma of the coffee will have substantially changed, and the continuing chemical composition change of the coffee with time will effectively result in a complete undesirable change in both flavor and aroma within a couple of hours. Accordingly, much coffee is wasted from the fact that it has "aged in the pot" and is thus discarded in favor or brewing a new fresh container thereof. This, of course, results in considerable wastage of freshly-brewed coffee, as well as the required labor and loss of time associated with the brewing thereof.
Recognizing these problems, the coffee industry has been continually attempting to develop a manner of coffee brewing which will permit the coffee to be brewed one cup at a time, while retaining freshness in flavor and intensity of aroma. The major recognized attempt at achieving this result is to be found in the marketing of various soluble instant coffees, whereby freeze-dried or similarly processed granules of ground coffee are provided for direct deposition in hot water. As is well known by the coffee-consuming public, instant coffee has very lttle of the aroma and flavor intensity of freshly-brewed coffee. However, the consuming public has been willing to accept the loss of aroma and flavor in return for the ease of brewing just one cup at a time while not necessitating any substantial amount of wasted time or subsequent cleaning of an associated coffee-brewing apparatus.
Inasmuch as instant coffee has not proved to be an acceptable solution to the problem of permitting the rapid brewing of coffee which retains intense flavor and aroma characteristics and which may be brewed one cup at a time without creating a situation where substantial subsequent cleaning must be performed, there is a continuing search for improvements in the coffee-brewing industry for effecting such a desired result. An early approach is to be found in U.S. Pat. No. 2,291,278, which issued to Cleaves on July 28, 1942, wherein there is disclosed a coffee bag which includes a rigid handle attached directly to the bag so as to facilitate its handling. The bag is identified as being constructed of a gauze or porous paper in the form of a container which holds the ground coffee, while the handle may be utilized to position the bag in a cup of hot water. As noted in the Cleaves' patent, it was at that time already known to utilize coffee bags having a string and tag attached thereto.
The Cleaves' patent is representative of a large number of patents directed to porous coffee bags designed for direct immersion in hot water. A more recent patent is U.S. Pat. No. 3,607,302, which issued to Beck on Sept. 21, 1971, with there being disclosed therein a coffee bag formed in a tubular manner which permits water flow in a longitudinal direction through a center section of the bag. While both of the inventions disclosed in these patents function to brew coffee in the manner described, certain serious shortcomings exist.
In this connection, it should be noted that the brewing of an ideal cup of coffee involves the extraction or entering into solution of some certain percentage, normally approximately 19 percent, of the dry weight of the ground coffee. Additionally, this extraction process must be performed rather rapidly in those cases where a continual supply of boiling hot water is not available. In other words, the brewing process can be performed slowly in the case of a percolator inasmuch as a continual supply of boiling hot water is directed over the coffee grounds; however, in the processes disclosed by Beck and Cleaves, it can be appreciated that rapid temperature decrease of the water will be experienced upon an insertion of the coffee bags into the water. After only a partial cooling of the water, the resulting chemical reaction is such as to destroy or hinder the development of desired flavor and aroma characteristics. By experiment, it has been shown that coffee bags constructed in the form of the Beck and Cleaves devices may be left to soak in hot water without ever achieving a desirable brewed state in an acceptable period of time.
Much of the problem with achieving the desired brewed state with the Beck and Cleaves devices arises from the fact that upon its immersion in hot water, coffee instantly begins to generate a large amount of gases, which could be caused both by chemical reaction and by the heat-effected expansion of the ambient air trapped between the coffee grounds. At the same time, a first and small portion of water soluble aromatic and flavorable oils are released from the ground coffee beans, and these essential oils tend to mix with the generated gases and air trapped between the coffee grains within the bag. As the gases expand, strong and elastic bubbles eventually occupy all of the available free space within the bag and as such, these gases cause the associated coffee bag to inflate whereby the bag tends to float on the surface of the hot water and at the same time, the pressurized gas bubbles within the bag effectively restrict the permeation of water through the bag. Additionally, the trapped gas tends to shield the individual coffee grounds from direct contact with such water as does manage to permeate through the bag, thereby to further slow the brewing process. As above-mentioned, the temperature of the water is rapidly decreasing during the brewing process and within a very short period of time, the efficiency of the coffee brewing process substantially decreases although an individual coffee bag may still be immersed in the water.
The problem of gas accumulation within a coffee bag does not appear to be rectified by increasing the porosity of the gauze or porous bag utilized to construct the coffee bag. In this respect, some of the coffee grounds rapidly dissolve into a residue of a size which will pass through paper or other material which is too porous and in fact, the size of pores actually needed to permit efficient gas venting would result in a substantial amount of the coffee grounds passing through the bag walls and entering directly into the brewed coffee solution. As such, it is necessary to maintain the use of small pores to prevent the depositing of a large amount of coffee grounds and associated residue into the hot brewing liquid.
There have been some prior attempts to deal with the problem of gas accummulation in coffee bags. One early attempt is to be found in U.S. Pat. No. 3,257,212, which issued to Kasket on June 21, 1966, with this patent disclosing a non-floating beverage package. The Kasket disclosure notes that coffee bags "have a tendency to rise up in the cup due to captured air bubbles and the light density of the materials within the bag." In an effort to overcome this problem, Kasket makes use of a coffee bag attached to a rigid handle with a weight means then being attached to a bottommost portion of the handle, whereby the coffee bag is forcibly retained beneath the surface of the brewing liquid irrespective of the fact that gas accumulation within the bag may occur. While this technique may be effective for the brewing of certain bullions, tea, or the like, it still does not overcome the problem of gas accumulation within the bag, whereby liquid permeation is restricted and coffee ground contact with the liquid is substantially retarded. As such, a slow coffee brewing rate is still experienced, whereby temperature drop of the brewing liquid has a chance to occur before the coffee is fully brewed and high coffee flavor and aroma intensity is not realized.
A further attempt at overcoming the problem of gas accumulation within a coffee bag is to be found in U.S. Pat. No. 3,879,565, which issued to Einstman et al. on Apr. 22, 1975. In this patent, there is disclosed the containment of roasted and ground coffee in a brewing bag in the manner above-described, with a defoaming agent, such as a silicone, being added to the coffee to disperse foam generated within the bag and to improve the rate of extraction of the coffee material. The Einstman patent recognizes the problem of gas entrapment by noting that the entrapped gas tends to retard extraction of the coffee material by apparently preventing good contact between the coffee and the extracting liquid. Einstman also notes that the increasing of the porosity of the infusion bags in order to permit an escape of the generated gases does not work because the increased porosity permits increased amounts of coffee grounds to escape from a bag, thereby producing an unsightly accummulation of sediment in the cup.
The defoaming agent of Einstman is spray plated on the surface of the roasted and ground coffee as a dilute dispersion or an emulsion with it being emphasized that the defoaming agents employed must be edible. While possibly functioning in the manner desired, it can be appreciated that it is not desirable to mix defoaming agents or any other chemicals with coffee grounds inasmuch as this could effect the flavor and aroma, and in any respect, the consuming public is resistant to purchasing foods having little-understood chemicals intermixed therewith.
As opposed to the coffee bag approach, there have been various other attempts, which may have been more or less successful, at brewing ground coffee in the manner of instant coffee. For example, U.S. Pat. No. 2,260,858, which issued to Naef on Oct. 28, 1941, discloses a dispensing device for making aromatic beverages which relies upon the use of a glass coffee grounds-holding container through which a plurality of perforations extend, whereby water may flow through the container and into contact with the coffee grounds. Of course, as abovediscussed, this construction permits substantial residue to accumulate in the brewed liquid and is thus undesirable. It should be noted that the construction illustrated in the Naef patent is illustrative of a plurality of such devices disclosed in the prior patent art. As such, it can be appreciated that there is a continuing need for improvement in the coffee brewing art, both with regard to apparatuses and methods for rapidly brewing ground coffee, and in this respect, the present invention substantially fulfills this need.